1. Field of the Invention
The present invention relates to an X-ray diagnostic apparatus, and particularly relates to setting of a radiation field of X-rays.
2. Description of the Related Art
Traditional X-ray diagnostic apparatus generally comprises a tabletop, an X-ray tube, and an X-ray detector. The tabletop is put a subject, the X-ray tube irradiates X-rays, and the X-ray detector detects X-rays that permeate the subject. The X-ray tube and X-ray detector are arranged on both sides of the tabletop. X-ray detecting elements are arranged to the detection range of the X-ray detector that detects X-rays.
A retention feature maintains the X-ray tube. The X-ray tube is composed movable along longer direction of the tabletop (direction of body axis of a subject) through the retention feature. The X-ray detector moves with the X-ray tube in a unified manner. The tabletop is composed movable along shorter direction of own.
A controller moves the tabletop, the retention feature, and the X-ray detector respectively according to the above-mentioned composition, and the center of the detection range of the X-ray detector can be matched to a test object of subject on the tabletop.
Four diaphragm blade units are located between the X-ray tube and the tabletop. A pair of diaphragm blade unit in the longer direction moves antithetically in the longer direction of the tabletop as a center of the detection range of the X-ray detector. A pair of diaphragm blade unit in the shorter direction moves antithetically in the shorter direction of the tabletop as a center of the detection range of the X-ray detector. Each a pair of diaphragm blade unit narrows the detection range of the X-ray detector from the longer direction of the tabletop and the shorter direction of the tabletop, and forms the exposure field on the X-ray detector. The diaphragm blade unit narrows the detection range of the X-ray detector, cuts unnecessary X-rays, prevents unnecessary radiation exposure, and improves the image quality of the radiographic view.
In the diagnostic radiography, first, an operator matches the center of the detection range of the X-ray detector to the test object of Subject. Concretely, the X-ray tube and the X-ray detector move to the longer direction of the tabletop, and the tabletop moves to the shorter direction of own. Next, the operator confirms the area in the detection range of the X-ray detector to the inspection object of the subject.
When the detection range of the X-ray detector is wide compared with the inspection object of the subject, it is necessary to narrow the detection range of the X-ray detector. Then, the diaphragm blade unit narrows the detection range of the X-ray detector and forms the exposure field on the X-ray detector. Next, the X-ray tube irradiates X-rays to the subject, the X-ray detector detects X-rays that passed the subject, the radiographic view is made and is displays it in the monitor.
When the test object of the subject is changed, the controller moves the tabletop, the retention feature, and the X-ray detector respectively to match the center of the detection range of the X-ray detector to the test object after it changes.
However, when the retention feature is moved, the center of the detection range of the X-ray detector might not be able to be matched to the test object of the subject, because the retention feature have a constant movement stroke's and evades interference with the tabletop etc. the retention feature, and the movement of the retention feature is limited. The retention feature is not stopped easily at a prescribed position, and there is a problem that easily matching the center of the detection range of the X-ray detector to the test object after it changes becomes difficult because the inertia of the retention feature is large. There is a problem of becoming a large encumbrance for the subject when the endoscope is inserted in the inside of the body of subject on the tabletop when the tabletop is moved.
When the test object of the subject is changed within the detection range of the X-ray detector, it only has to operate each a pair of diaphragm blade unit and to expand the exposure field. The test object of the subject can be fit in the broadening exposure field. As a result, the retention feature need not move. However, the retention field expands and outside of test object is unnecessarily exposed to radiation.
To correspond to the change of test object of the subject without expanding exposure field, the controller open and shut each a pair of diaphragm blade unit individually, to move exposure field within the detection range of the X-ray detector, and to match the center of exposure field to the test object of the subject.
However, a past device has the problem that the operation of the diaphragm blade unit becomes complex, because it needs the opening and closing operation of each diaphragm blade unit to do the opening and closing movement individually as for each diaphragm blade unit.
As for a past technology, the X-ray tube and the X-ray detector are composed as one body and rotatably. When it changes the test object of the subject, the X-ray tube and the diaphragm blade unit are rotated as one body, and moves the center of the exposure field to the test object after it changes.
As for a past technology, it has an edge detector of the edge of the X-ray detector and rotates as one body the X-ray tube and diaphragm blade unit, and moves the center of the exposure field. When the edge of the exposure field of X rays hangs to the edge detector, one side of a pair of diaphragm blade unit is individually moved from the edge to the center, and the controller limits it so that an X-ray beam doesn't exceed the detection range of the X-ray detector.
However, the above-mentioned technology needs the mechanism that composes the X-ray tube and diaphragm blade unit as one body and rotatably. It needs the other mechanism to drive the mechanism.